This invention is directed to the field of structured textile materials that are made of at least two different base nonwoven fabrics, and which find particular application as a cleaning textile.
A cleaning textile, made of a structured textile material composed of at least two base nonwoven fabrics, is known from WO 94 23 634. Furthermore, WO 90 14 039 shows a structured, textile, surface-area material that is made of one nonwoven fabric, from which a multitude of thread loops or fiber ends are raised by needling.
A method for its manufacture is disclosed in the British patent 2 162 213. There, the structures are produced by needling a nonwoven fabric, such that fibers or filaments are pulled out from the opposite surface with the assistance of barbs. As a consequence of this method, the structures are made principally from material taken from the respective opposite surface.
The disadvantage of known structured textile materials made of at least two different, unbonded base nonwoven fabrics is that in needling the two unbonded base nonwoven fabrics, a base nonwoven fabric in a mixed color results on the side where the needle comes out. When producing the structures by through-needling the fibers of one base nonwoven fabric through the other base nonwoven fabric, further mixed effects also result which degrade the appearance of the finished textile material and also weaken the specific service properties of the fibrous material of a base nonwoven fabric.
There remains a need for a structured textile material formed from at least two different base nonwoven fabrics, in which such a mixture of the fibers is avoided.
According to the invention, the base nonwoven fabrics have a structure obtained by needling from at least one side. The needles used for the structure needling are fork needles or crown needles, and the depth of the forks and barbs, respectively, are selected so that when piercing through, they fill up completely with fibers of the base nonwoven fabric facing the needles. Consequently, the textile material produced is characterized by unmixed, pure fibers in the pattern, in the background and on the reverse side.
A textile material having these features has the advantage that the specific service properties of the fibrous material of a base nonwoven fabric are retained during the structuring. In the case where base nonwoven fabrics of different colors are used, the pure original colors are maintained in the pattern, both in the background and on the reverse side. This permits the attainment of various desired visual effects.
To increase the interlaminar strength of the textile, the base nonwoven fabrics, having thermoplastic fibers, can be laminated to one another, and the bonding of the two base nonwoven fabrics can then be further strengthened by activating the vertically positioned thermoplastic fibers. In principle, all known methods and all known binding agents are usable for the laminating, however, it is preferable to utilize those known methods that impart a good bond and a negligible stiffening of the textile material, and furnish a launderability of at least 60xc2x0 C., and preferably 95xc2x0 C.
Advantageously, at least one base nonwoven fabric contains thermoplastic fibers whose properties are so selected that they are not activated during the laminating stage. It then becomes possible to provide the unbonded base nonwoven fabrics with the desired structures by needling.
In the same way, the lamination of the two base nonwoven fabrics can be augmented by an intermediate layer made of a material capable of glueing the two base nonwoven fabrics together. This intermediate layer can take the form of an adhesive nonwoven fabric (such as a layer of fibers bonded with adhesives) that can be introduced between the two base nonwoven fabrics having thermoplastic fibers. The two base nonwoven fabrics and the intermediate layer can be bonded by activating the thermoplastic fibers and the intermediate layer. While it is possible that portions of the intermediate layer will be needled into the structure, this is desirable under some circumstances, and can be exploited to increase the interlaminar strength.
Although, in general, the choice of the sides of the nonwoven fabrics to be joined does not matter for the present invention, it is advantageous that the pierce-through sides of the base nonwoven fabrics, reinforced by needling from one side, be facing one another.
To intensify the effect of the structurings, the base nonwoven fabrics can have different material properties, particularly as relating to cleaning ability.
One method according to the invention calls for laminating the two needled base nonwoven fabrics having thermoplastic fibers, without activating the thermoplastic fibers. A structure-needling process is subsequently carried out on one or two sides, and is followed by the activation of the thermoplastic fibers of the base nonwoven fabrics. The result is a structured textile material that is made of at least two different base nonwoven fabrics having structures on one or two both sides formed by needling, in which the textile material retains unmixed, pure fibers in the pattern, in the background and on the reverse side.
Compared to a textile material made of two different nonwoven fabrics needled together, one has the advantage that, until the structuring, the base nonwoven fabrics remain unmixed. The needed strength of the base nonwoven fabrics is obtained by separate needling of the two base nonwoven fabrics before the lamination process.
In another method, prior to feeding the textile laminate into a structure-needling machine, an intermediate layer made of a material capable of glueing the two base nonwoven fabrics, in particular an adhesive nonwoven fabric, is introduced between the two needled base nonwoven fabrics having thermoplastic fibers. The two base nonwoven fabrics and the intermediate layer are subjected together to a structure-needling process on one or two sides. Subsequently, the two base nonwoven fabrics and the intermediate layer are bonded by activating the thermoplastic fibers and the intermediate layer. The result is a structured textile material that is made of at least two varicolored base nonwoven fabrics and has structures on one or two sides formed by needling, the textile material having unmixed, pure fibers in the pattern, in the background and on the reverse side.
This method is especially suited for one-sided structuring. However, it is also usable for structuring on both sides if so much stability is produced by the first pattern, applied on one side, that a second passage is possible without shifting the layers relative to each other.
To attain the best possible purity of the fibers, the process should is advantageously conducted such that the fork needles or crown needles used for the structure needling step completely fill up with fibers of the base nonwoven fabric facing the needles as they pierce them.